Kitchel
annealing furnace seal

ABSTRACT

A SEAL FOR ELIMINATING OR REDUCING AIR INFILTRATION INTO AN INNER COVER OF A STEEL ANNEALING FURNACE INCLUDING A TUBE OF WOVEN METAL REINFORCED CERAMIC STRAND FILLED WITH CERAMIC FIBERS IN BULK FORM ON WHICH THE BOTTOM OF THE INNER COVER RESTS.

- v Jim; 9, 1973 F. L. KITCHEL. Re. 27,543

ANNEALING FURNACE SEAL Original Filed Nov. 2. 1967 2 Sheets-Sheet 1 4 2[III 4 I I I I I ll I, I I I I ll LA; I I I 20 8 l4 INl/E/V ran.

FR ED L. K/TCHE'L Wlm All larnoy Jon. 9.1973 F. 1.. KITCHEL ANNBALINGFURNACE SEAL 2 Shqets-$heet 2.

Original Filed Nov. 2, 1967 INVENTOR. FRED L. Kl TCHEL A! funny UnitedStates Patent Int. Cl. F27b /00 US. Cl. 263-40 8 Claims Matter enclosedin bean brackets appears in the original patent but forms no part ofthis reissue specification; matter printed in italics indicates theadditions made by reissue.

ABSTRACT OF THE DISCLOSURE A seal for eliminating or reducing airinfiltration into an inner cover of a steel annealing furnace includinga tube of woven metal reinforced ceramic strand filled with ceramicfibers in bulk form on which the bottom of the inner cover rests.

This invention relates to a seal and more particularly to a seal forpreventing infiltration of air into the inner cover of a batch typeannealing furnace. Such furnaces, sometimes called bell annealingfurnaces, include a base upon which coils of steel strip are stackedwith a removable inner cover on the base. One or more such bases arearranged beneath a removable outer cover carrying heating means thereon.An annealing atmosphere is circulated by means of a fan within eachinner cover and it is necessary to provide a seal to preventinfiltration of air into the inner cover and escape of atmosphere fromthe inner cover. A sand seal is most commonly used for this purpose.This includes a channel for the sand in which the inner cover rests.Such a seal is shown in Dailey Patent No. 2,489,012 dated Nov. 22, 1949.Sand seals have various disadvantages, the most important one being thata portion of the sand sometimes contacts the strip being annealed andcauses sand pits which results in a loss of production. It also requiresabout an hour of a workmans time to prepare the sand seal for each use.Liquid seals have also been used to some extent, but these two havedisadvantages. Due to the heat the liquid may vaporize and contaminatethe seal strip. There are also problems in handling the liquid. It hasalso been proposed to use a refractory seal of alumina silicate as shownin Cone Patent No. 2,854,226 dated Sept. 30, 1958. However, as disclosedtherein this seal has various disadvantages. It requires the use of twoseals, one a metal-to-metal seal for supporting the majority of theweight of the inner cover, this being necessary to prevent injury to thesealing medium by shearing or permanent deformation. There is also atendency for the material to stick to the inner cover.

It is therefore an object of my invention to provide a seal which willeliminate or greatly decrease the quality loss of the material beingheat treated.

Another object is to provide such a seal which can be readily handledand which need not be prepared for each use.

Still another object is to provide a refractory seal that can supportthe full weight of the inner cover.

These and other objects will be more apparent after referring to thefollowing specification and attached drawings, in which:

FIGURE 1 is a sectional view of an inner annealing cover and supportingstructure with my seal incorporated therein;

FIGURE 2 is a view taken on line II-II of FIGURE 1. but showing only onehalf of the furnace;

FIGURE 3 is an enlarged view taken on line IIIIII ofFIGURE 2;

FIGURE 4 is an enlarged view of the connection between the ends of theseal member; and

FIGURE 5 is an enlarged view of a portion of FIG URE 3 showing the shapeof the seal member at various stages in its use.

Referring more particularly to the drawings, reference numeral 2indicates the base of an annealing furnace for supporting a coil C ofsteel strip. A fan 4 is used to circulate atmosphere through and aroundthe coil C beneath a corrugated inner cover 6 which is preferably madeof stainless steel. A vertical skirt 8 is provided at the lower end ofthe cover 6. The base 2 includes a circumferential vertical steel plate10. According to any invention, 1 provide a trough 12 which surroundsthe circular base 2 below the top thereof. Inner leg 14 of the troughextends upwardly parallel to the plate 10 and a plurality of gussetplates 16 extend between and are welded to the plates 10 and 14 inspaced apart relationship. The top of the gusset plates 16 taperdownwardly and outwardly to form guides 18 for the cover 16. Sealingmember 20 of my invention consists of a flexible woven textile tube 22filled with bulk fiber 24. The member 20 extends around the completeperiphery of trough 12 and has its ends joined in any suit able manner.For example, the tube 22 may have one end 26 tucked within the other end28 as shown in FIGURE 4. The tube 22 consists of ceramic strandsreinforced with any metal resistant to oxidation at high temperatures.Various fibrous ceramic materials such as asbestos, glass fiber andmineral wool that can be spun and woven into a heat resistant cloth aresuitable as long as the ceramic material possesses a high softeningpoint and good resilience. Similar ceramic material can be used in theunspun or bulk condition for the filling 24. One suitable material usedfor this purpose has a composition of 51.3% A1 0 45.3% SiO and 3.4% ZrOand is sold under the trade name Fiberfrax by the Carborundum Company.Cords of this material impregnated with Nichrome wire reinforcement arewoven into cloth for this purpose. Similarly the fibrous filling 24 mayhave a composition of 50.9% A1203, Slog, B203, N320 and .3% to .5miscellaneous inorganic material. This material can withstandtemperatures up to 2300 F. The member 20 should essentially fill thetrough 12. The diameter of the tube 22 is preferably equal to the widthW of the trough 12 although the width W could be as much as inch greateror /2 inch less than the diameter of the tube and sitll functionproperly.

In operation, the member 20 is placed in the trough 12 and will assumesubstantially circular form as shown in full lines in FIGURE 5. Afterthe charge is placed on the base 2, the inner cover 6 is lowered intothe trough 12 with the guides 18 positioning the inner cover 6 in thedesired position on the member 20. The diameter of leg 8 of the innercover is generally equal to the diameter of trough 12 at the centerthereof, but may vary therefrom. The variation preferably should notexeed 2 inches. When the leg 8 of the inner cover 6 is lowered onto themember 20 it Will depress the upper part of it approximately to thebroken line position 22A shown in FIGURE 5. When the inner cover isremoved the member 20 will expand somewhat upwardly to approximately thedashdot line 223 shown in FIGURE '5. When the inner cover 6 is lowered asecond and subsequent time the guides 18 will return the inner cover torelatively the same position so that a better seal and longer life isprovided. I have found that the member 20 has sufiicient strength tosupport the full weight of the inner cover, that it has sufficientresiliency toprovide a very good seal and that it will not contaminatethe charge.

While one embodiment of my invention has been hown and described, itwill be apparent that other adapations and modifications may be made.

I claim:

1. In a furnace having a base, a peripheral trough surounding said base,said trough having inner and outer ides, and a cover adapted to surroundsaid base with its )Wer end in said trough, the improvement comprising a.exi ble woven tube made of ceramic strands reinforced with metalresistant to oxidation at high temperatures, nd bulk ceramic filler insaid tube, the length and cross ection of said filled tube being such asto extend comletely around the periphery of the trough in bearing en-;agement with the sides of the trough.

2. The combination of claim 1 in which the trough has :enerallyconcentric inner and outer legs, the outside dimeter of said tube beingapproximately equal to the disance between said inner and outer legs.

3. The combination of claim 1 including guides for said over around theperiphery of said base extending downvardly and outwardly from a pointadjacent the top of aid base to the inner side of said trough.

4. The combination of claim 3 in which the trough has ;enerallyconcentric inner and outer legs, the outside dimeter of said tube beingapproximately equal to the disance between said inner and outer legs.

5. In a furnace having a base, a peripheral trough urrounding said base,said trough having inner and outer ides, and a cover adapted to surroundsaid base with its ower end in said trough, the improvement comprising alexible resilient sealing member having sufficzent strength support thefull weight of said inner cover, said sealing nember including aflexible tube made of high heat reistant material, and filler materialin said tube made of high heat resistant material, the length and crosssection of said sealing member being such as to extend completely aroundthe periphery of the trough in bearing engagement with the sides of thetrough.

6. The combination of claim 5 in which the trough has generallyconcentric inner and outer legs, the outside diameter of said tube beingapproximately equal to the distance between said inner and outer legs.

7. The combination of claim 5 including guides for said cover around theperiphery of said base extending downwardly and outwardly from a pointadjacent the top of said base to the inner side of said trough.

8. The combination of claim 7 in which the trough has generallyconcentric inner and outer legs, the outside diameter of said tube beingapproximately equal to the distance between said inner and outer legs.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 1,892,112 12/1932 Moore et a1. 26341 X 2,849,2208/1958 Duffy et a1. 263-42 TH 2,964,307 12/1960 Van Dine 263 3,179,3944/1965 Sims et a1 266-5 B 3,411,763 11/1968 Blackman et a1 34242 X JOHNJ. CAMBY, Primary Examiner US. Cl. X.R.

